Exposure of humans to high levels of woodsmoke is associated with adverse health effects including impaired lung function, asthma, respiratory disease and cardiovascular disease. In the US alone, more than 100,000 people annually are exposed to elevated woodsmoke levels from wildfires, prescribed burns and agricultural field burning. 70,000 - 80,000 people involved in wildland fire fighting also receive substantial occupational exposure to woodsmoke. Investigating the relationship between woodsmoke exposure and adverse health effects is hindered by inadequate methods of exposure assessment, which lead to exposure misclassification. Consequently, the setting of occupational exposure limits and community-impact-driven guidelines for managed fires suffers from a lack of exposure-response data. The primary objective of this proposal is to develop biological markers of human exposure to woodsmoke. Preliminary work has shown that levels of a number of substituted methoxylated phenolic compounds are increased in urine following woodsmoke exposure. It is our hypothesis that the dose- dependent increase in urinary methoxyphenols observed following ingestion or inhalation of woodsmoke combustion products can be related in a quantitative manner to environmental woodsmoke, and thereby provide a biomarker basis for assessment of woodsmoke exposure in occupationally and environmentally exposed populations. To test this hypothesis, we plan to measure methoxyphenol levels in urine samples collected from wildfire fighters who have elevated occupational exposure to woodsmoke. Firefighter exposures to fine particles (PM2.5), CO and levoglucosan (LG, a woodsmoke-specific tracer) will be characterized. Urinary methoxyphenols will be determined before and after woodsmoke exposure (pre- and post-shift), by using GC/MS techniques. Regression models will be developed to predict the associations between cross-shift changes in creatinine-corrected urinary concentrations of specific methoxyphenols and measurements of woodsmoke exposure (PM2.5, CO, LG). We shall evaluate the effect of inter-individual variation in methoxyphenol uptake, metabolism and urinary excretion by assessing within and between subject variance in the woodsmoke exposure-biomarker response relationship. Additionally, the influence of fuel type upon exposure to specific methoxyphenols, and consequently upon the relationship between urinary methoxyphenol biomarkers and smoke exposure will be explored. A validated biomarker of woodsmoke exposure will facilitate exposure assessment for studies investigating adverse effects of woodsmoke exposure in humans, and could be used to evaluate the effectiveness of interventions to reduce woodsmoke exposure in domestic and occupational settings. This proposed study addresses NORA research priorities related to asthma and COPD, indoor environment, exposure assessment methods and control technology/personal protective equipment. Environmental and occupational exposures to wood smoke cause adverse respiratory health effects. We propose to measure woodsmoke chemicals in human urine in order to determine how much wood smoke an individual has breathed in. These improved measures of smoke exposure will help us to better understand the link between smoke exposures and health problems, and hence will guide health policy in the setting of exposure standards that are adequately protective of public health. [unreadable] [unreadable] [unreadable]